Knitted fleece fabrics have been used for cold weather insulation either in standalone garments or garment components. These fleece fabrics are usually made with polyester or cotton fiber on plush/terry, or 2-end, 3-end or similar knitting machines. The fabric is then napped and sometimes sheared to make the pile. A pile surface can be formed on one or both sides of the fabric. Typically, 2-end and 3-end fabrics are napped on only one side of the fabric and plush/terry fabrics may be napped on one or both sides of the fabric. These fabrics may contain different fibers in the pile yarn and in the ground/stitch yarn and, if a 3-end knit, in the tie yarn of the fabric. See U.S. Pat. No. 5,727,401, the entirety of which is incorporated by reference. The resilient polyester fiber is low cost, a good insulator, launderable with good appearance and insulation characteristics, hydrophobic, still insulative when wet, and quick drying. These characteristics are all helpful for good performance in cold weather clothing.
There is a need for cold weather insulating materials for workers who may be exposed to flash fires, other thermal exposures, and arcs in the course of performing their jobs. Employees in the petro-chemical and electrical utility areas frequently work outdoors and face both flash fire and electrical arc thermal threats. They need thermally resistant cold weather insulation garments.
Unfortunately, polyester fleece burns and melts upon exposure to the types of thermal threats encountered in those occupations. This of course presents a potential danger to wearers of polyester and other non-thermally resistant fleece materials. Efforts have been made to produce flame resistant fleece fabrics, but they have been based on aramid fiber which is difficult to dye and in many cases prohibitively expensive. Other flame resistant fleece material has high (>50%) levels of modacrylic fibers, which, although less expensive than aramid fibers, have some negative characteristics. Many of those modacrylic fabrics tend to have poor pile loft and poor afterwash appearance. The poor pile loft, especially after laundering, may result in lower insulation levels for a given weight of material. The poor appearance may be the result of either matting or pilling of the modacrylic fiber surface. The modacrylic fiber is simply not stiff or resilient enough to make good pile. In addition, these modacrylic blends have high thermal shrinkage (>10%) and high char length (>4 inches) and thus typically will not satisfy the requirements of NFPA 2112.